Reports of COVID-19 Vaccine Adverse Events in Predominantly Republican vs Democratic States

Key Points Question Is state political inclination associated with COVID-19 vaccine adverse event (AE) reporting? Findings This cross-sectional study of 620 456 AE reports found that a 10% increase in state Republican voting was associated with a 5% increase in the odds that a COVID-19 vaccine AE would be reported, a 25% increase in the odds that a severe AE would be reported, and a 21% increase in the odds that any reported AE would be severe. Meaning The findings suggest that the more states are inclined to vote Republican, the more likely their vaccine recipients or their clinicians are to report COVID-19 vaccine AEs.


eAppendix 1. Data Sources
Data used for this study were obtained from the following sources, accessed 07.25.2023 • The VAERS data were downloaded from https://vaers.hhs.gov/data/datasets.html.

eAppendix 2. Statistical Modeling
The straight lines in the manuscript Figure were fitted by linear regression weighted by both sample size and residual heteroskedasticity.Specifically, a linear regression of The smoothing curves in the manuscript Figure were fitted by the locally estimated scatterplot smoothing (LOESS) lines.The local estimate at each point was calculated using all data and tricubic weighting of distance, and each state weighted by its total vaccine administration (R function loess).This smooth fitting was also applied to the FLU vaccines AE reporting, the curves are shown below, with no obvious positive nor negative association between percent of Republican in 2020 presidential election and FLU vaccine AE reporting rates.The logistic regression model in the manuscript was fit for the three outcomes separately.Here we used the first outcome, e.g.VAERS AE reports among all vaccinated, as an example to illustrate the model setting.Denote  0 and  1 as the counts of VAERS reports (numerators), and  0 and  1 the total number of vaccinated (denominators) for influenza and COVID19 vaccines respectively in the i th state.The logistic regression assumes  1 ~( 1 ,  1 ) and: ), and   ,   ,   ,   are state Male/Female ratio, state median age, and state 2020 Republican vote percentage, respectively.The above regression was also fit in each of the age strata 18-49, 50-64 and 65+, where the state median age variable was not included.The results are shown in Table S3.The association between political inclination and any of the three reporting rates is stronger in older populations.
As the first sensitivity analyses, we developed hierarchical logistic regression models for both COVID and influenza vaccines AE reporting.Instead of directly adjusting for the influenza vaccine reporting rate (i.e. the  ( ) term in the above regression), we included state-specific random effects to account for heterogeneity in baseline VAERS reporting rate.The model was (  ) =   +   *   +   *   +   *  0 +   *   +   *   * ,  = 0,1.
Here   's are state-specific random intercepts,   is the indicator for COVID vaccines ( = 1) and   is the effect of COVID vaccines compared to influenza vaccines.The coefficient  represents the interested political effect of COVID vaccines compared to influenza vaccines.This hierarchical logistic regression was also fitted within each age strata.The results are in Table S4 and again show that the association between political inclination and any of the three reporting rates is stronger in older populations.
As another sensitivity analysis, we further performed an individual-level analysis within the VAERS reports for outcome (3), i.e. severe reports among all reported.For each of the VAERS report, while the political inclination was still state-level, the individual-level age, sex, and history of medication or allergy were now available.Vaccines other than COVID are used as reference (instead of influenza vaccines).We fit hierarchical logistic regression with state-level random intercepts.The age effect may be nonlinear so we used splines (b-spline with d.f.=4, degree=3) for individual age.We also allowed the political effects to be interacted with vaccine type, sex, age and history for potential effect modifiers.The political effects are shown in Figure S1.The political effect on severe AE reports for COVID vaccines is the same significant between male and female, not significant for those with history of medication or allergy, and stronger among older individuals for COVID vaccines.The political effect is not significant for vaccines other than COVID vaccines.

eTable 1 .
State-Level Political Inclination and Counts of Vaccine Administered and VAERS AE ReportsThe numbers in the parentheses are number per 10,000 administered.